Semiconductor device with redistribution structure and method for fabricating the same

ABSTRACT

The present application discloses a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device includes a first chip including: a first inter-dielectric layer positioned on a first substrate; a plug structure positioned in the first inter-dielectric layer and electrically coupled to a functional unit of the first chip; a first redistribution layer positioned on the first inter-dielectric layer and distant from the plug structure; a first lower bonding pad positioned on the first redistribution layer; and a second lower bonding pad positioned on the plug structure; and a second chip positioned on the first chip and including: a first upper bonding pad positioned on the first lower bonding pad; a second upper bonding pad positioned on the second lower bonding pad; and a plurality of storage units electrically coupled to the first upper bonding pad and the second upper bonding pad.

TECHNICAL FIELD

The present disclosure relates to a semiconductor device and a methodfor fabricating the semiconductor device, and more particularly, to asemiconductor device with a redistribution structure and a method forfabricating the semiconductor device with the redistribution structure.

DISCUSSION OF THE BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cellular telephones, digital cameras, andother electronic equipment. The dimensions of semiconductor devices arecontinuously being scaled down to meet the increasing demand ofcomputing ability. However, a variety of issues arise during thescaling-down process, and such issues are continuously increasing.Therefore, challenges remain in achieving improved quality, yield,performance, and reliability and reduced complexity.

This Discussion of the Background section is provided for backgroundinformation only. The statements in this Discussion of the Backgroundare not an admission that the subject matter disclosed in this sectionconstitutes prior art to the present disclosure, and no part of thisDiscussion of the Background section may be used as an admission thatany part of this application, including this Discussion of theBackground section, constitutes prior art to the present disclosure.

SUMMARY

One aspect of the present disclosure provides a semiconductor deviceincluding a first chip including: a first inter-dielectric layerpositioned on a first substrate; a plug structure positioned in thefirst inter-dielectric layer and electrically coupled to a functionalunit of the first chip; a first redistribution layer positioned on thefirst inter-dielectric layer and distant from the plug structure; afirst lower bonding pad positioned on the first redistribution layer;and a second lower bonding pad positioned on the plug structure; and asecond chip positioned on the first chip and including: a first upperbonding pad positioned on the first lower bonding pad; a second upperbonding pad positioned on the second lower bonding pad; and a pluralityof storage units electrically coupled to the first upper bonding pad andthe second upper bonding pad.

In some embodiments, the first chip is configured as a logic chip andthe second chip is configured as a memory chip.

In some embodiments, the plug structure includes a bottom plugpositioned on the first substrate, a landing pad positioned on thebottom plug, and a top plug positioned between the landing pad and thesecond lower bonding pad.

In some embodiments, the semiconductor device includes a first barrierlayer positioned between the top plug and the second lower bonding pad.

In some embodiments, the semiconductor device includes a second barrierlayer positioned between the landing pad and the top plug.

In some embodiments, the semiconductor device includes a third barrierlayer positioned between the top plug and the second lower bonding pad,and a fourth barrier layer positioned between the first lower bondingpad and the first redistribution layer.

In some embodiments, a bottom surface of the third barrier layer is at avertical level lower than a top surface of the first redistributionlayer.

In some embodiments, a width of the first chip and a width of the secondchip are substantially the same.

In some embodiments, the bottom plug includes aluminum, copper, or acombination thereof, and the top plug includes tungsten.

In some embodiments, the third barrier layer includes titanium andtitanium nitride.

In some embodiments, the plurality of storage units are configured as acapacitor array or a floating array.

Another aspect of the present disclosure provides a semiconductor deviceincluding a first chip including: a first substrate including a centerregion and a peripheral region surrounding the center region; a firstcenter bonding pad positioned above the center region of the firstsubstrate; and a first peripheral bonding pad positioned above theperipheral region of the first substrate; and a second chip positionedon the first chip and including: a plurality of peripheral upper bondingpads located at a peripheral region of the second chip and respectivelypositioned on the first center bonding pad and the first peripheralbonding pad; a plurality of redistribution structures respectivelypositioned on the plurality of peripheral upper bonding pads andextending toward a center region of the second chip; a plurality ofcenter lower bonding pads located at the center region of the secondchip and respectively positioned on the plurality of redistributionstructures; and a plurality of storage units electrically coupled to theplurality of center lower bonding pads.

In some embodiments, the plurality of redistribution structures include:a plurality of redistribution layers respectively positioned on theplurality of peripheral upper bonding pads, and respectively extendingfrom the peripheral region of the second chip toward the center regionof the second chip; and a plurality of redistribution plugs located atthe center region of the second chip, and positioned between theplurality of center lower bonding pads and the plurality ofredistribution layers, respectively and correspondingly.

In some embodiments, the semiconductor device includes a plurality offirst supporting plugs respectively positioned on the plurality ofredistribution layers, wherein the plurality of first supporting plugsare distant from the plurality of redistribution plugs and the pluralityof first supporting plugs are floating.

In some embodiments, the semiconductor device includes a plurality ofsecond supporting plugs respectively positioned on the plurality ofredistribution layers, wherein the plurality of second supporting plugsare distant from the plurality of first supporting plugs and theplurality of second supporting plugs are floating.

In some embodiments, a distance between an adjacent pair of theplurality of redistribution plugs and the plurality of first supportingplugs and a distance between an adjacent pair of the plurality of firstsupporting plugs and the plurality of second supporting plugs aresubstantially the same.

In some embodiments, the semiconductor device includes a molding layerpositioned on the first chip and covering the second chip.

Another aspect of the present disclosure provides a method forfabricating a semiconductor device including providing a first substrateincluding a functional unit; forming a plug structure on the firstsubstrate and electrically coupled to the functional unit; forming afirst redistribution layer above the first substrate; forming a firstlower bonding pad on the first redistribution layer; forming a secondlower bonding pad on the plug structure, wherein the first substrate,the plug structure, the first redistribution layer, the first lowerbonding pad, and the second lower bonding pad together configure a firstchip; and bonding a second chip onto the first chip. The second chipincludes a first upper bonding pad bonded on the first lower bondingpad, a second upper bonding pad bonded on the second lower bonding pad,and a plurality of storage units electrically coupled to the first upperbonding pad and the second upper bonding pad.

In some embodiments, the first chip is configured as a logic chip andthe second chip is configured as a memory chip, and the plurality ofstorage units are configured as a capacitor array or a floating array.

In some embodiments, the plug structure includes a bottom plug formed onthe first substrate, a landing pad formed on the bottom plug, and a topplug formed on the landing pad.

Due to the design of the semiconductor device of the present disclosure,data signal may be transmitted through the first upper bonding pad, thefirst lower bonding pad, and the first redistribution layer withoutpassing through the conductive features, the plug structure, andfunctional units of the first chip. As a result, the distance oftransmittance may be reduced so that the performance of thesemiconductor device may be improved. In addition, the power consumptionof the semiconductor device may be reduced due to the shorter distanceof transmittance

The foregoing has outlined rather broadly the features and technicaladvantages of the present disclosure in order that the detaileddescription of the disclosure that follows may be better understood.Additional features and advantages of the disclosure will be describedhereinafter, and form the subject of the claims of the disclosure. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures or processes for carrying outthe same purposes of the present disclosure. It should also be realizedby those skilled in the art that such equivalent constructions do notdepart from the spirit and scope of the disclosure as set forth in theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 illustrates, in a flowchart diagram form, a method forfabricating a semiconductor device in accordance with one embodiment ofthe present disclosure;

FIGS. 2 to 8 illustrate, in schematic cross-sectional view diagrams, aflow for fabricating the semiconductor device in accordance with oneembodiment of the present disclosure;

FIGS. 9 to 11 illustrate, in schematic cross-sectional view diagrams,semiconductor devices in accordance with some embodiments of the presentdisclosure;

FIG. 12 illustrates, in a schematic top-view diagram, part of a flow forfabricating a semiconductor device in accordance with another embodimentof the present disclosure;

FIG. 13 is a schematic cross-sectional view diagram taken along a lineA-A′ in FIG. 12 ;

FIG. 14 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device in accordance with anotherembodiment of the present disclosure;

FIG. 15 is a schematic cross-sectional view diagram taken along a lineA-A′ in FIG. 14 ;

FIG. 16 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device in accordance with anotherembodiment of the present disclosure;

FIG. 17 is a schematic cross-sectional view diagram taken along a lineA-A′ in FIG. 16 ;

FIG. 18 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device in accordance with anotherembodiment of the present disclosure;

FIG. 19 is a schematic cross-sectional view diagram taken along a lineA-A′ in FIG. 18 ; and

FIGS. 20 to 23 illustrate, in schematic cross-sectional view diagrams,part of the flow for fabricating the semiconductor device in accordancewith another embodiment of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

It should be understood that when an element or layer is referred to asbeing “connected to” or “coupled to” another element or layer, it can bedirectly connected to or coupled to another element or layer, orintervening elements or layers may be present.

It should be understood that, although the terms first, second, etc. maybe used herein to describe various elements, these elements should notbe limited by these terms. Unless indicated otherwise, these terms areonly used to distinguish one element from another element. Thus, forexample, a first element, a first component or a first section discussedbelow could be termed a second element, a second component or a secondsection without departing from the teachings of the present disclosure.

Unless the context indicates otherwise, terms such as “same,” “equal,”“planar,” or “coplanar,” as used herein when referring to orientation,layout, location, shapes, sizes, amounts, or other measures do notnecessarily mean an exactly identical orientation, layout, location,shape, size, amount, or other measure, but are intended to encompassnearly identical orientation, layout, location, shapes, sizes, amounts,or other measures within acceptable variations that may occur, forexample, due to manufacturing processes. The term “substantially” may beused herein to reflect this meaning. For example, items described as“substantially the same,” “substantially equal,” or “substantiallyplanar,” may be exactly the same, equal, or planar, or may be the same,equal, or planar within acceptable variations that may occur, forexample, due to manufacturing processes.

In the present disclosure, a semiconductor device generally means adevice which can function by utilizing semiconductor characteristics,and an electro-optic device, a light-emitting display device, asemiconductor circuit, and an electronic device are all included in thecategory of the semiconductor device.

It should be noted that, in the description of the present disclosure,above (or up) corresponds to the direction of the arrow of the directionZ, and below (or down) corresponds to the opposite direction of thearrow of the direction Z.

It should be noted that, in the description of the present disclosure,the terms “forming,” “formed” and “form” may mean and include any methodof creating, building, patterning, implanting, or depositing an element,a dopant, or a material. Examples of forming methods may include, butare not limited to, atomic layer deposition, chemical vapor deposition,physical vapor deposition, sputtering, co-sputtering, spin coating,diffusing, depositing, growing, implantation, photolithography, dryetching, and wet etching.

It should be noted that, in the description of the present disclosure,the functions or steps noted herein may occur in an order different fromthe order noted in the figures. For example, two figures shown insuccession may in fact be executed substantially concurrently or maysometimes be executed in a reversed order, depending upon thefunctionalities or steps involved.

FIG. 1 illustrates, in a flowchart diagram form, a method 10 forfabricating a semiconductor device 1A in accordance with one embodimentof the present disclosure. FIGS. 2 to 8 illustrate, in schematiccross-sectional view diagrams, a flow for fabricating the semiconductordevice 1A in accordance with one embodiment of the present disclosure.

With reference to FIGS. 1 to 4 , at step S11, a first substrate 111 maybe provided, a first redistribution layer 131 may be formed above thefirst substrate 111, and a plug structure 121 may be formed on the firstsubstrate 111.

With reference to FIG. 2 , in some embodiments, the first substrate 111may include a bulk semiconductor substrate that is composed entirely ofat least one semiconductor material, a plurality of device elements (notshown for clarity), a plurality of dielectric layers (not shown forclarity), and a plurality of conductive features (not shown forclarity). The bulk semiconductor substrate may be formed of, forexample, an elementary semiconductor, such as silicon or germanium; acompound semiconductor, such as silicon germanium, silicon carbide,gallium arsenide, gallium phosphide, indium phosphide, indium arsenide,indium antimonide, or other III-V compound semiconductor or II-VIcompound semiconductor; or combinations thereof.

In some embodiments, the first substrate 111 may further include asemiconductor-on-insulator structure which consisting of, from bottom totop, a handle substrate, an insulator layer, and a topmost semiconductormaterial layer. The handle substrate and the topmost semiconductormaterial layer may be formed of a same material as the bulksemiconductor substrate aforementioned. The insulator layer may be acrystalline or non-crystalline dielectric material such as an oxideand/or nitride. For example, the insulator layer may be a dielectricoxide such as silicon oxide. For another example, the insulator layermay be a dielectric nitride such as silicon nitride or boron nitride.For yet another example, the insulator layer may include a stack of adielectric oxide and a dielectric nitride such as a stack of, in anyorder, silicon oxide and silicon nitride or boron nitride. The insulatorlayer may have a thickness between about 10 nm and 200 nm.

It should be noted that, in the description of present disclosure, theterm “about” modifying the quantity of an ingredient, component, orreactant of the present disclosure employed refers to variation in thenumerical quantity that can occur, for example, through typicalmeasuring and liquid handling procedures used for making concentrates orsolutions. Furthermore, variation can occur from inadvertent error inmeasuring procedures, differences in the manufacture, source, or purityof the ingredients employed to make the compositions or carry out themethods, and the like. In one aspect, the term “about” means within 10%of the reported numerical value. In another aspect, the term “about”means within 5% of the reported numerical value. Yet, in another aspect,the term “about” means within 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% of thereported numerical value.

The plurality of device elements may be formed on the first substrate111. Some portions of the plurality of device elements 111 may be formedin the first substrate 111. The plurality of device elements may betransistors such as complementary metal-oxide-semiconductor transistors,metal-oxide-semiconductor field-effect transistors, finfield-effect-transistors, the like, or a combination thereof.

The plurality of dielectric layers may be formed on the first substrate111 and covering the plurality of device elements. In some embodiments,the plurality of dielectric layers may be formed of, for example,silicon oxide, borophosphosilicate glass, undoped silicate glass,fluorinated silicate glass, low-k dielectric materials, the like, or acombination thereof. The low-k dielectric materials may have adielectric constant less than 3.0 or even less than 2.5. In someembodiments, the low-k dielectric materials may have a dielectricconstant less than 2.0. The plurality of dielectric layers may be formedby deposition processes such as chemical vapor deposition,plasma-enhanced chemical vapor deposition, or the like. Planarizationprocesses may be performed after the deposition processes to removeexcess material and provide a substantially flat surface for subsequentprocessing steps.

The plurality of conductive features may include interconnect layers,conductive vias, and conductive pads. The interconnect layers may beseparated from each other and may be horizontally disposed in theplurality of dielectric layers along the direction Z. In the presentembodiment, the topmost interconnect layers may be designated as theconductive pads. The conductive vias may connect adjacent interconnectlayers along the direction Z, adjacent device element and interconnectlayer, and adjacent conductive pad and interconnect layer. In someembodiments, the conductive vias may improve heat dissipation and mayprovide structure support. In some embodiments, the plurality ofconductive features may be formed of, for example, tungsten, cobalt,zirconium, tantalum, titanium, aluminum, ruthenium, copper, metalcarbides (e.g., tantalum carbide, titanium carbide, tantalum magnesiumcarbide), metal nitrides (e.g., titanium nitride), transition metalaluminides, or a combination thereof. The plurality of conductivefeatures may be formed during the formation of the plurality ofdielectric layers.

The plurality of device elements, and the plurality of conductivefeatures may together configure functional units. A functional unit, inthe description of the present disclosure, generally refers tofunctionally related circuitry that has been partitioned for functionalpurposes into a distinct unit. In some embodiments, functional units maybe typically highly complex circuits such as processor cores oraccelerator units. In some other embodiments, the complexity andfunctionality of a functional unit may be more or less complex.

With reference to FIG. 2 , a bottom dielectric layer 115 may be formedon the first substrate 111. In some embodiments, the bottom dielectriclayer 115 may be formed of, for example, silicon oxide,borophosphosilicate glass, undoped silicate glass, fluorinated silicateglass, low-k dielectric materials, the like, or a combination thereof.The bottom dielectric layer 115 may be formed by deposition processessuch as chemical vapor deposition, plasma-enhanced chemical vapordeposition, or the like. Planarization processes may be performed afterthe deposition processes to remove excess material and provide asubstantially flat surface for subsequent processing steps.

With reference to FIG. 2 , a bottom plug 123 may be formed along thebottom dielectric layer 115 and electrically coupled to thecorresponding one of device element in the first substrate 111. In otherwords, the bottom plug 123 may be in conjunction with the functionalunits in the first substrate 111. In some embodiments, the bottom plug123 may be formed of, for example, tungsten, cobalt, zirconium,tantalum, titanium, aluminum, ruthenium, copper, metal carbides (e.g.,tantalum carbide, titanium carbide, tantalum magnesium carbide), metalnitrides (e.g., titanium nitride), transition metal aluminides, or acombination thereof. In the present embodiments, the bottom plug 123 maybe formed of an alloy of aluminum and copper.

With reference to FIG. 2 , a landing pad 125 may be formed on the bottomplug 123. The width W1 of the landing pad 125 may be greater than thewidth W2 of the bottom plug 123. In some embodiments, the landing pad125 may be formed of, for example, tungsten, cobalt, zirconium,tantalum, titanium, aluminum, ruthenium, copper, metal carbides (e.g.,tantalum carbide, titanium carbide, tantalum magnesium carbide), metalnitrides (e.g., titanium nitride), transition metal aluminides, or acombination thereof. In some embodiments, the landing pad 125 may beformed by performing a blanket deposition process with followingpatterning and etching processes.

With reference to FIG. 3 , a top dielectric layer 117 may be formed onthe bottom dielectric layer 115 and covering the landing pad 125. Thetop dielectric layer 117 may be formed of the same material as thebottom dielectric layer 115, and descriptions thereof are not repeatedherein. The top dielectric layer 117 may be formed by a depositionprocess such as chemical vapor deposition, plasma-enhanced chemicalvapor deposition, or the like. A planarization process may be performedafter the deposition process to remove excess material and provide asubstantially flat surface for subsequent processing steps. The bottomdielectric layer 115 and the top dielectric layer 117 may togetherconfigure a first inter-dielectric layer 113.

With reference to FIG. 3 , the first redistribution layer 131 may beformed on the first inter-dielectric layer 113. In some embodiments, thefirst redistribution layer 131 may be formed of, for example, tungsten,cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper,metal carbides (e.g., tantalum carbide, titanium carbide, tantalummagnesium carbide), metal nitrides (e.g., titanium nitride), transitionmetal aluminides, or a combination thereof. In some embodiments, thefirst redistribution layer 131 may be formed by performing a blanketdeposition process with following patterning and etching processes. Itshould be noted that the first redistribution layer 131 does notelectrically couple to any functional units in the first substrate 111.

With reference to FIG. 4 , a first bottom passivation layer 141 may beformed on the first inter-dielectric layer 113 and covering the firstbottom passivation layer 141. In some embodiments, the first bottompassivation layer 141 may be formed of, for example, silicon oxide,silicon nitride, silicon oxynitride, silicon nitride oxide, siliconcarbon nitride, the like, or a combination thereof. In some embodiments,the bottom passivation layer 141 may be formed of, for example, apolymer layer including polyimide, polybenzoxazole, benzocyclobuten,epoxy, silicone, acrylates, nano-filled phenoresin, siloxane, afluorinated polymer, polynorbornene, or the like. A planarizationprocess may be performed until the top surface 131TS of the firstredistribution layer 131 is exposed to remove excess material andprovide a substantially flat surface for subsequent processing steps.

It should be noted that, in the description of the present disclosure, asurface of an element (or a feature) located at the highest verticallevel along the direction Z is referred to as a top surface of theelement (or the feature). A surface of an element (or a feature) locatedat the lowest vertical level along the direction Z is referred to as abottom surface of the element (or the feature).

With reference to FIG. 4 , a top plug 127 may be formed along the firstbottom passivation layer 141, extending to the top dielectric layer 117,and on the landing pad 125. The width W3 of the top plug 127 may begreater than the width W1 of the bottom plug 123. The width W3 of thetop plug 127 may be less than the width W2 of the landing pad 125. Insome embodiments, the top plug 127 may be formed of, for example,tungsten, cobalt, zirconium, tantalum, titanium, aluminum, ruthenium,copper, metal carbides (e.g., tantalum carbide, titanium carbide,tantalum magnesium carbide), metal nitrides (e.g., titanium nitride),transition metal aluminides, or a combination thereof. A patterningprocess with a mask layer (not shown for clarity), which masks the firstredistribution layer 131, may be performed to form a plug opening (notshown for clarity) to expose a portion of the landing pad 125. Asubsequent deposition process may be performed to deposit theaforementioned material to fill the plug opening. A planarizationprocess may be performed until the top surface 131TS of the firstredistribution layer 131 is exposed to remove excess material andconcurrently form the top plug 127. In the present embodiment, the topplug 127 may include tungsten.

The bottom plug 123, the landing pad 125, and the top plug 127 maytogether configure the plug structure 121. The plug structure 121 mayelectrically couple to the corresponding one of device element in thefirst substrate 111. In other words, the plug structure 121 may be inconjunction with the functional units in the first substrate 111.

With reference to FIGS. 1, 5, and 6 , at step S13, a first lower bondingpad 151 may be formed on the first redistribution layer 131, and asecond lower bonding pad 153 may be formed on the plug structure 121,wherein the first substrate 111, the plug structure 121, the firstredistribution layer 131, the first lower bonding pad 151, and thesecond lower bonding pad 153 together configure a first chip 100.

With reference to FIG. 5 , a first top passivation layer 143 may beformed on the first bottom passivation layer 141. In some embodiments,the first top passivation layer 143 may be formed of a polymericmaterial such as polybenzoxazole, polyimide, benzocyclobutene, ajinomotobuildup film, solder resist film, or the like. The polymeric material(e.g., polyimide) may have a number of attractive characteristics suchas the ability to fill openings of high aspect ratio, a relatively lowdielectric constant (about 3.2), a simple depositing process, thereduction of sharp features or steps in the underlying layer, and hightemperature tolerance after curing. In some embodiments, the first toppassivation layer 143 may be formed by, for example, spin-coating,lamination, deposition, or the like. The deposition may include chemicalvapor deposition such as plasma-enhanced chemical vapor deposition. Theprocess temperature of the plasma-enhanced chemical vapor deposition maybe between about 350° C. and about 450° C. The process pressure of theplasma-enhanced chemical vapor deposition may be between about 2.0 Torrand about 2.8 Torr. The process duration of the plasma-enhanced chemicalvapor deposition may be between about 8 seconds and about 12 seconds.

With reference to FIG. 5 , in some embodiments, a plurality of padopenings 145, 147 may be formed along the first top passivation layer143. The first redistribution layer 131 may be exposed through the padopening 145 and the top plug 127 may be exposed through the pad opening147. The plurality pad openings 145, 147 may be formed by aphotolithography process and a subsequent etching process. In someembodiments, the etching process may be an anisotropic dry etchingprocess using argon and tetrafluoromethane as etchants. The processtemperature of the etching process may be between about 120° C. andabout 160° C. The process pressure of the etching process is betweenabout 0.3 Torr and about 0.4 Torr. The process duration of the etchingprocess may be between about 33 seconds and about 39 seconds.Alternatively, in some embodiments, the etching process may be ananisotropic dry etching process using helium and nitrogen trifluoride asetchants. The process temperature of the etching process may be betweenabout 80° C. and about 100° C. The process pressure of the etchingprocess is between about 1.2 Torr and about 1.3 Torr. The processduration of the etching process may be between about 20 seconds andabout 30 seconds.

With reference to FIG. 6 , a conductive material may be formed to fillthe plurality pad openings 145, 147 to form the first lower bonding pad151 and the second lower bonding pad 153, respectively andcorrespondingly. In some embodiments, the conductive material may be,for example, tungsten, cobalt, zirconium, tantalum, titanium, aluminum,ruthenium, copper, metal carbides (e.g., tantalum carbide, titaniumcarbide, tantalum magnesium carbide), metal nitrides (e.g., titaniumnitride), transition metal aluminides, or a combination thereof. In someembodiments, the plurality pad openings 145, 147 may be sequentiallyfilled with the conductive material by sputtering or electrolessplating. For example, when the plurality pad openings 145, 147 arefilled by sputtering using an aluminum-copper material as source, theprocess temperature of sputtering may be between about 100° C. and about400° C. The process pressure of sputtering may be between about 1 mTorrand about 100 mTorr. For another example, the plurality pad openings145, 147 may be filled by an electroplating process using a platingsolution. The plating solution may include copper sulfate, coppermethane sulfonate, copper gluconate, copper sulfamate, copper nitrate,copper phosphate, or copper chloride. The pH of the plating solution maybe between about 2 and about 6 or between about 3 and about 5. Theprocess temperature of the electroplating process may be maintainedbetween about 40° C. and about 75° C. or between about 50° C. and about70° C.

With reference to FIG. 6 , the first lower bonding pad 151 may be formedin the pad opening 145 and may be electrically connected to the firstredistribution layer 131. It should be noted that the first lowerbonding pad 151 does not electrically couple to any functional units inthe first substrate 111. The second lower bonding pad 153 may be formedin the pad opening 147 and may be electrically connected to the top plug127. That is, the second lower bonding pad 153 may be in conjunctionwith the functional units in the first substrate 111 through the plugstructure 121.

With reference to FIG. 6 , the first substrate 111, the firstinter-dielectric layer 113, the plug structure 121, the firstredistribution layer 131, the first bottom passivation layer 141, thefirst top passivation layer 143, the first lower bonding pad 151, andthe second lower bonding pad 153 together configure the first chip 100.In some embodiments, the first chip 100 may be configured as a logicchip. The first chip 100 may include a front surface 100FS. It should benoted that, in the description of the present disclosure, the term“front” surface is a term of art implying the major surface of thestructure upon which is formed device elements and conductive features.In the present embodiment, the front surface 100FS of the first chip 100may be the top surface of the first top passivation layer 143.

With reference to FIGS. 1 and 7 , at step S15, a second chip 200 may beprovided and including a plurality of storage units 221, a first upperbonding pad 241, and a second upper bonding pad 243.

With reference to FIG. 7 , the second chip 200 may include a secondsubstrate 211, a plurality of second device elements (not shown forclarity), a second inter-dielectric layer 213, a plurality of secondconductive features (not shown for clarity), the plurality of storageunits 221, a second top passivation layer 231, the first upper bondingpad 241, and the second upper bonding pad 243.

With reference to FIG. 7 , in some embodiments, the second substrate 211may be a bulk semiconductor substrate that is composed entirely of atleast one semiconductor material; the bulk semiconductor substrate doesnot contain any dielectrics, insulating layers, or conductive features.The bulk semiconductor substrate may be formed of, for example, anelementary semiconductor, such as silicon or germanium; a compoundsemiconductor, such as silicon germanium, silicon carbide, galliumarsenide, gallium phosphide, indium phosphide, indium arsenide, indiumantimonide, or other III-V compound semiconductor or II-VI compoundsemiconductor; or combinations thereof.

In some embodiments, the second substrate 211 may include asemiconductor-on-insulator structure which consisting of, from bottom totop, a handle substrate, an insulator layer, and a topmost semiconductormaterial layer. The handle substrate and the topmost semiconductormaterial layer may be formed of a same material as the bulksemiconductor substrate aforementioned. The insulator layer may be acrystalline or non-crystalline dielectric material such as an oxideand/or nitride. For example, the insulator layer may be a dielectricoxide such as silicon oxide. For another example, the insulator layermay be a dielectric nitride such as silicon nitride or boron nitride.For yet another example, the insulator layer may include a stack of adielectric oxide and a dielectric nitride such as a stack of, in anyorder, silicon oxide and silicon nitride or boron nitride. The insulatorlayer may have a thickness between about 10 nm and 200 nm.

The plurality of second device elements may be formed on the secondsubstrate 211. Some portions of the plurality of second device elementsmay be formed in the second substrate 211. The plurality of seconddevice elements may be transistors such as complementarymetal-oxide-semiconductor transistors, metal-oxide-semiconductorfield-effect transistors, fin field-effect-transistors, the like, or acombination thereof.

With reference to FIG. 7 , the second inter-dielectric layer 213 may beformed on the second substrate 211 and cover the plurality of seconddevice elements. The second inter-dielectric layer 213 may be a stackedlayer structure. The second inter-dielectric layer 213 may include aplurality of insulating sub-layers (not shown for clarity). Each of theplurality of insulating sub-layers may have a thickness between about0.5 micrometer and about 3.0 micrometer. The plurality of insulatingsub-layers may be formed of, for example, silicon oxide,borophosphosilicate glass, undoped silicate glass, fluorinated silicateglass, low-k dielectric materials, the like, or a combination thereof.The plurality of first insulating sub-layers may be formed of differentmaterials but is not limited thereto.

The plurality of second conductive features may include interconnectlayers, conductive vias, and conductive pads. The interconnect layersmay be separated from each other and may be horizontally disposed in thesecond inter-dielectric layer 213 along the direction Z. In the presentembodiment, the topmost interconnect layers may be designated as theconductive pads. The conductive vias may connect adjacent interconnectlayers along the direction Z, adjacent second device element andinterconnect layer, and adjacent conductive pad and interconnect layer.In some embodiments, the conductive vias may improve heat dissipationand may provide structure support. In some embodiments, the plurality ofsecond conductive features may be formed of, for example, tungsten,cobalt, zirconium, tantalum, titanium, aluminum, ruthenium, copper,metal carbides (e.g., tantalum carbide, titanium carbide, tantalummagnesium carbide), metal nitrides (e.g., titanium nitride), transitionmetal aluminides, or a combination thereof. The plurality of secondconductive features may be formed during the formation of the secondinter-dielectric layer 213.

With reference to FIG. 7 , the plurality of storage units 221 may beformed in the second inter-dielectric layer 213 and may electricallycouple to the plurality of second conductive features. In someembodiments, the plurality of storage units 221 may be configured as acapacitor array. In some embodiments, the plurality of storage units 221may be configured as a floating array.

With reference to FIG. 7 , the second top passivation layer 231 may beformed on the second inter-dielectric layer 213. In some embodiments,the second top passivation layer 231 may be formed of a polymericmaterial such as polybenzoxazole, polyimide, benzocyclobutene, ajinomotobuildup film, solder resist film, or the like. The polymeric material(e.g., polyimide) may have a number of attractive characteristics suchas the ability to fill openings of high aspect ratio, a relatively lowdielectric constant (about 3.2), a simple depositing process, thereduction of sharp features or steps in the underlying layer, and hightemperature tolerance after curing. In some embodiments, the second toppassivation layer 231 may be formed by, for example, spin-coating,lamination, deposition, or the like. The deposition may include chemicalvapor deposition such as plasma-enhanced chemical vapor deposition. Theprocess temperature of the plasma-enhanced chemical vapor deposition maybe between about 350° C. and about 450° C. The process pressure of theplasma-enhanced chemical vapor deposition may be between about 2.0 Torrand about 2.8 Torr. The process duration of the plasma-enhanced chemicalvapor deposition may be between about 8 seconds and about 12 seconds.

With reference to FIG. 7 , the first upper bonding pad 241 and thesecond upper bonding pad 243 may be formed in the second top passivationlayer 231. In some embodiments, pad openings (not shown in FIG. 7 ) maybe formed in the second top passivation layer 231 and a conductivematerial may be formed to fill the pad openings to form the first upperbonding pad 241 and the second upper bonding pad 243. The pad openingmay be formed by a photolithography process and a subsequent etchingprocess. In some embodiments, the etching process may be an anisotropicdry etching process using argon and tetrafluoromethane as etchants. Theprocess temperature of the etching process may be between about 120° C.and about 160° C. The process pressure of the etching process is betweenabout 0.3 Torr and about 0.4 Torr. The process duration of the etchingprocess may be between about 33 seconds and about 39 seconds.Alternatively, in some embodiments, the etching process may be ananisotropic dry etching process using helium and nitrogen trifluoride asetchants. The process temperature of the etching process may be betweenabout 80° C. and about 100° C. The process pressure of the etchingprocess is between about 1.2 Torr and about 1.3 Torr. The processduration of the etching process may be between about 20 seconds andabout 30 seconds. In some embodiments, the conductive material may be,for example, tungsten, cobalt, zirconium, tantalum, titanium, aluminum,ruthenium, copper, metal carbides (e.g., tantalum carbide, titaniumcarbide, tantalum magnesium carbide), metal nitrides (e.g., titaniumnitride), transition metal aluminides, or a combination thereof.

In some embodiments, the pad openings may be sequentially filled withthe conductive material by sputtering or electroless plating. Forexample, when the pad opening are filled by sputtering using analuminum-copper material as source, the process temperature ofsputtering may be between about 100° C. and about 400° C. The processpressure of sputtering may be between about 1 mTorr and about 100 mTorr.For another example, the pad openings may be filled by an electroplatingprocess using a plating solution. The plating solution may includecopper sulfate, copper methane sulfonate, copper gluconate, coppersulfamate, copper nitrate, copper phosphate, or copper chloride. The pHof the plating solution may be between about 2 and about 6 or betweenabout 3 and about 5. The process temperature of the electroplatingprocess may be maintained between about 40° C. and about 75° C. orbetween about 50° C. and about 70° C.

In some embodiments, the second chip 200 may be configured as a memorychip. The first upper bonding pad 241 and the second upper bonding pad243 may be configured to serve as input/output of the memory chip. Thesecond chip 200 may include a front surface 200FS. In the presentembodiment, the front surface 200FS of the second chip 200 may be thetop surface of the second top passivation layer 231.

With reference to FIGS. 1 and 8 , at step S17, the second chip 200 maybe bonded onto the first chip 100 to form the semiconductor device 1A.

With reference to FIG. 8 , the second chip 200 may be bonded onto thefirst chip 100 in a face-to-face configuration through a hybrid bondingprocess. The front surface 200FS of the second chip 200 may be bondedonto the front surface 100FS of the first chip 100. After the hybridbonding process, the second chip 200 (configured as the memory chip) andthe first chip 100 (configured as the logic chip) may together configurean integrated circuit package. For example, the second upper bonding pad243 may be disposed on the second lower bonding pad 153. That is, thesecond upper bonding pad 243 may be in conjunction with the functionalunits of the first chip 100 through the plug structure 121. Signal suchas control signal may be transmitted from the first chip 100 to theplurality of storage units 221 through the plug structure 121, thesecond lower bonding pad 153, and the second upper bonding pad 243. Thefirst upper bonding pad 241 may be disposed on the first lower bondingpad 151. Signal such as data signal may be transmitted from theplurality of storage units 221 through the first upper bonding pad 241,the first lower bonding pad 151, and the first redistribution layer 131to an external reading unit without passing through the conductivefeatures, the plug structure 121, and functional units of the first chip100.

In some embodiments, the hybrid bonding process may be, for example,thermo-compression bonding, passivation-capping-layer assisted bonding,or surface activated bonding. For example, the hybrid bonding processmay include activating exposed surfaces of the second top passivationlayer 231 of the second chip 200 and the first top passivation layer 143(e.g., in a plasma process), cleaning the second top passivation layer231 and the first top passivation layer 143 after activation, contactingthe activated surface of the second top passivation layer 231 and theactivated surface of the first top passivation layer 143, and performinga thermal annealing process to strengthen the bonding between the secondtop passivation layer 231 and the first top passivation layer 143.

In some embodiments, the process pressure of the hybrid bonding processmay be between about 100 MPa and about 150 MPa. In some embodiments, theprocess temperature of the hybrid bonding process may be between aboutroom temperature (e.g., 25° C.) and about 400° C. In some embodiments,surface treatments such as wet chemical cleaning and gas/vapor-phasethermal treatments may be used to lower the process temperature of thehybrid bonding process or to shorten the time consuming of the hybridbonding process.

In some embodiments, the hybrid bonding process may includedielectric-to-dielectric bonding, metal-to-metal bonding, andmetal-to-dielectric bonding. The dielectric-to-dielectric bonding mayoriginate from the bonding between the second top passivation layer 231and the first top passivation layer 143. The metal-to-metal bonding mayoriginate from the bonding between the first upper bonding pad 241 andthe first lower bonding pad 151, and between the second upper bondingpad 243 and the second lower bonding pad 153. The metal-to-dielectricbonding may originate from the bonding between the first top passivationlayer 143 and the first upper bonding pad 241 and the second upperbonding pad 243, and between the second top passivation layer 231 andthe first lower bonding pad 151 and the second lower bonding pad 153.

In some embodiments, when the first top passivation layer 143 and thesecond top passivation layer 231 are formed of, for example, siliconoxide or silicon nitride, the bonding between the first top passivationlayer 143 and the second top passivation layer 231 may be based on thehydrophilic bonding mechanism. Hydrophilic surface modifications may beapplied to the first top passivation layer 143 and the second toppassivation layer 231 before bonding.

In some embodiments, when the first top passivation layer 143 and thesecond top passivation layer 231 are formed of polymer adhesives such aspolyimide, benzocyclobutenes, and polybenzoxazole, the bonding betweenthe first top passivation layer 143 and the second top passivation layer231 may be based on thermo-compression bonding.

In some embodiments, a thermal annealing process may be performed afterthe bonding process to enhance dielectric-to-dielectric bonding and toinduce thermal expansion of metal-to-metal bonding so as to furtherimprove the bonding quality.

With reference to FIG. 8 , in some embodiments, the width W4 of thefirst chip 100 and the width W5 of the second chip 200 may besubstantially the same.

FIGS. 9 to 11 illustrate, in schematic cross-sectional view diagrams,semiconductor devices 1B, 1C, and 1D in accordance with some embodimentsof the present disclosure.

With reference to FIG. 9 , the semiconductor device 1B may include afirst barrier layer 161 disposed between the first top passivation layer143 and the second lower bonding pad 153, between the top plug 127 andthe second lower bonding pad 153, and between the second lower bondingpad 153 and the first bottom passivation layer 141. The first barrierlayer 161 may be formed of, for example, titanium, titanium nitride, ora combination thereof. The first barrier layer 161 may be formed by, forexample, atomic layer deposition, physical vapor deposition, chemicalvapor deposition, or other applicable deposition process.

With reference to FIG. 10 , the semiconductor device 1C may include asecond barrier layer 163 disposed between the first bottom passivationlayer 141 and the top plug 127, between the top dielectric layer 117 andthe top plug 127, and between the landing pad 125 and the top plug 127.The second barrier layer 163 may be formed of the same material as thefirst barrier layer 161, and descriptions thereof are not repeatedherein.

With reference to FIG. 11 , in the semiconductor device 1D, a secondbarrier layer 163 may be disposed between the first bottom passivationlayer 141 and the top plug 127, between the top dielectric layer 117 andthe top plug 127, and between the landing pad 125 and the top plug 127.In some embodiments, the second barrier layer 163 may have a U-shapedcross-sectional profile extending toward the landing pad 125. The topsurface of the second barrier layer 163 and the top surface of the topplug 127 may be recessed to a vertical level VL1 between the top surface131TS and the bottom surface 131BS of the first redistribution layer131. A third barrier layer 165 may be conformally disposed between thesecond lower bonding pad 153 and the top plug 127. In some embodiments,the third barrier layer 165 may further include a U-shaped protrusion165-1 extending toward the top plug 127 and disposed on the top surfaceof the top plug 127. In other words, the bottom surface 165BS of theU-shaped protrusion 165-1 (i.e., the bottom surface of the third barrierlayer 165) may be lower than the top surface 131TS of the firstredistribution layer 131 and higher than top surface 131TS and thebottom surface 131BS of the first redistribution layer 131. Accordingly,the second lower bonding pad 153 may further include a protrusionportion 155 extending toward the top plug 127 and disposed in the recessconfigured by the U-shaped protrusion 165-1. In some embodiments, thebottom surface 165BS of the U-shaped protrusion 165-1 may be rounding.In some embodiments, the bottom surface 165BS of the U-shaped protrusion165-1 may be substantially flat. A fourth barrier layer 167 may beconformally disposed between the first lower bonding pad 151 and thefirst redistribution layer 131. The third barrier layer 165 and thefourth barrier layer 167 may be formed of a same material as the firstbarrier layer 161, and descriptions thereof are not repeated herein.

FIG. 12 illustrates, in a schematic top-view diagram, part of a flow forfabricating a semiconductor device 1E in accordance with anotherembodiment of the present disclosure. FIG. 13 is a schematiccross-sectional view diagram taken along a line A-A′ in FIG. 12 .

With reference to FIGS. 12 and 13 , a third substrate 311 may beprovided. The third substrate 311 may include a center region CR1 and aperipheral region PL1 surrounding the center region CR1. A third bottominter-dielectric layer 313 may be formed on the third substrate 311. Aplurality of storage units 321 may be formed in the third bottominter-dielectric layer 313. In some embodiments, the plurality ofstorage units 321 may be configured as capacitor array. In someembodiments, the plurality of storage units 321 may be configured asfloating array. A plurality of interconnection layers 315 may be formedin the third bottom inter-dielectric layer 313 and may be electricallycoupled to the plurality of storage units 321. A third bottompassivation layer 331 may be formed on the third bottom inter-dielectriclayer 313. A plurality of center lower bonding pads 341 may be formed onthe plurality of interconnection layers 315, respectively andcorrespondingly. The plurality of center lower bonding pads 341 may belocated at the center region CR1.

The third substrate 311, the third bottom inter-dielectric layer 313,the third bottom inter-dielectric layer 313, the plurality of storageunits 321, the plurality of interconnection layers 315, the third bottompassivation layer 331, and the plurality of center lower bonding pads341 may be formed with procedures similar to the second substrate 211,the second inter-dielectric layer 213, the plurality of storage units221, the second conductive features, the second top passivation layer231, and the first upper bonding pad 241, respectively andcorrespondingly, and descriptions thereof are not repeated herein.

FIG. 14 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device 1E in accordance with anotherembodiment of the present disclosure. FIG. 15 is a schematiccross-sectional view diagram taken along a line A-A′ in FIG. 14 .

With reference to FIGS. 14 and 15 , a third top inter-dielectric layer317 may be formed on the third bottom passivation layer 331. A pluralityof redistribution plugs 353 may be formed on the plurality of centerlower bonding pads 341, respectively and correspondingly. The pluralityof redistribution plugs 353 may be formed in the third topinter-dielectric layer 317 and may be located at the center region CR1.A plurality of first supporting plugs 361 and a plurality of secondsupporting plugs 363 may be formed in the third top inter-dielectriclayer 317.

For brevity, clarity, and convenience of description, only oneredistribution plug 353, one first supporting plug 361, and one secondsupporting plug 363 are described. The distance D1 between the adjacentpair of the redistribution plug 353 and the first supporting plug 361 isabout the same as the distance D2 between the adjacent pair of the firstsupporting plug 361 and the second supporting plug 363.

The third top inter-dielectric layer 317, the redistribution plug 353,the first supporting plug 361, and the second supporting plug 363 may beformed with procedures similar to the third bottom passivation layer 331and the top plug 127, respectively and correspondingly, and descriptionsthereof are not repeated herein.

FIG. 16 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device 1E in accordance with anotherembodiment of the present disclosure. FIG. 17 is a schematiccross-sectional view diagram taken along a line A-A′ in FIG. 16 .

With reference to FIGS. 16 and 17 , a plurality of second redistributionlayers 355 may be formed on the third top inter-dielectric layer 317.For brevity, clarity, and convenience of description, only one secondredistribution layer 355 is described. The second redistribution layer355 may be formed on the redistribution plug 353, the first supportingplug 361, and the second supporting plug 363. The redistribution plug353 and the second redistribution layer 355 may together configure aredistribution structure 351. The first supporting plug 361 and thesecond supporting plug 363 may be floating. The first supporting plug361 and the second supporting plug 363 may provide additional supportingduring a following bonding process as will be illustrated later. Thesecond redistribution layer 355 may be formed with a procedure similarto the first redistribution layer 131, and descriptions thereof are notrepeated herein.

FIG. 18 illustrates, in a schematic top-view diagram, part of the flowfor fabricating a semiconductor device 1E in accordance with anotherembodiment of the present disclosure. FIG. 19 is a schematiccross-sectional view diagram taken along a line A-A′ in FIG. 18 .

With reference to FIGS. 18 and 19 , a third top passivation layer 333may be formed on the third top inter-dielectric layer 317 to cover theplurality of second redistribution layers 355. A plurality of peripheralupper bonding pads 343 may be formed on the plurality of secondredistribution layers 355, respectively and correspondingly. Theplurality of peripheral upper bonding pads 343 may be formed in thethird top passivation layer 333 and may be located at the peripheralregion PL1.

The third substrate 311, the third bottom inter-dielectric layer 313,the plurality of interconnection layers 315, the third topinter-dielectric layer 317, the plurality of storage units 321, thethird bottom passivation layer 331, the plurality of center lowerbonding pads 341, the plurality of redistribution structures 351, theplurality of first supporting plugs 361, the plurality of secondsupporting plugs 363, the third top passivation layer 333, and theplurality of peripheral upper bonding pads 343 together configure athird chip 300. In some embodiments, the third chip 300 may beconfigured as a memory chip. The plurality of peripheral upper bondingpads 343 may be configured as input/output of the third chip 300. Theplurality of redistribution structures 351 may in conjunction with theplurality of center lower bonding pads 341 to transmit signal of theplurality of storage units 321 from center region CR2 to the pluralityof peripheral upper bonding pads 343 which are at peripheral region PL1of the third chip 300.

FIGS. 20 to 23 illustrate, in schematic cross-sectional view diagrams,part of the flow for fabricating the semiconductor device 1E inaccordance with another embodiment of the present disclosure.

With reference to FIG. 20 , a fifth chip 500 may be provided. The fifthchip 500 may include a fifth substrate 511, a fifth inter-dielectriclayer 513, a fifth top passivation layer 533, a plurality of fifthcenter bonding pads 541, and a plurality of fifth peripheral bondingpads 543. The fifth substrate 511 may include a center region CR2 and aperipheral region PL2 surrounding the center region CR2. The fifthinter-dielectric layer 513 may be formed on the fifth substrate 511. Thefifth top passivation layer 533 may be formed on the fifthinter-dielectric layer 513. The plurality of fifth center bonding pads541 and the plurality of fifth peripheral bonding pads 543 may be formedin the fifth top passivation layer 533. The plurality of fifth centerbonding pads 541 may be located at the center region CR2 and theplurality of fifth peripheral bonding pads 543 may be located at theperipheral region PL2.

The fifth substrate 511, the fifth inter-dielectric layer 513, the fifthinter-dielectric layer 513, the plurality of fifth center bonding pads541, and the plurality of fifth peripheral bonding pads 543 may beformed with procedures similar to the first substrate 111, the firstinter-dielectric layer 113, the first top passivation layer 143, and thefirst lower bonding pad 151, respectively and correspondingly, anddescriptions thereof are not repeated herein. In some embodiments, thefifth chip 500 may be configured as a logic chip.

With reference to FIG. 21 , a fourth chip 400 may be formed with aprocedure similar to the third chip 300, and descriptions thereof arenot repeated herein. The third chip 300 may be bonded onto the fifthchip 500 through a hybrid bonding process similar to that illustrated inFIG. 8 , and descriptions thereof are not repeated herein. In someembodiments, the width W6 of the third chip 300 is less than the widthW7 of the fifth chip 500. After the bonding processes, the plurality ofperipheral upper bonding pads 343 may be bonded onto the fifth centerbonding pad 541 and the fifth peripheral bonding pad 543, respectivelyand correspondingly. The fourth chip 400 may be bonded onto the fifthchip 500 with a procedure similar to the third chip 300, anddescriptions thereof are not repeated herein.

With reference to FIG. 22 , a molding layer 611 may be formed on thefifth chip 500 to cover the third chip 300 and the fourth chip 400. Insome embodiments, the molding layer 611 may be formed of a moldingcompound such as polybenzoxazole, polyimide, benzocyclobutene, epoxylaminate, or ammonium bifluoride. The molding layer 611 may be formed bycompressive molding, transfer molding, liquid encapsulant molding, andthe like. For example, a molding compound may be dispensed in liquidform. Subsequently, a curing process is performed to solidify themolding compound. The formation of molding compound may overflow theintermediate semiconductor device illustrated in FIG. 21 so that moldingcompound may completely cover the third chip 300 and the fourth chip400. The third chip 300, the fourth chip 400, the fifth chip 500, andthe molding layer 611 together configure the semiconductor device 1E.

One aspect of the present disclosure provides a semiconductor deviceincluding a first chip including: a first inter-dielectric layerpositioned on a first substrate; a plug structure positioned in thefirst inter-dielectric layer and electrically coupled to a functionalunit of the first chip; a first redistribution layer positioned on thefirst inter-dielectric layer and distant from the plug structure; afirst lower bonding pad positioned on the first redistribution layer;and a second lower bonding pad positioned on the plug structure; and asecond chip positioned on the first chip and including: a first upperbonding pad positioned on the first lower bonding pad; a second upperbonding pad positioned on the second lower bonding pad; and a pluralityof storage units electrically coupled to the first upper bonding pad andthe second upper bonding pad.

Another aspect of the present disclosure provides a semiconductor deviceincluding a fifth chip including: a fifth substrate including a centerregion and a peripheral region surrounding the center region; a fifthcenter bonding pad positioned above the center region of the fifthsubstrate; and a fifth peripheral bonding pad positioned above theperipheral region of the fifth substrate; and a third chip positioned onthe fifth chip and including: a plurality of peripheral upper bondingpads located at a peripheral region of the third chip and respectivelypositioned on the fifth center bonding pad and the fifth peripheralbonding pad; a plurality of redistribution structures respectivelypositioned on the plurality of peripheral upper bonding pads andextending toward a center region of the third chip; a plurality ofcenter lower bonding pads located at the center region of the third chipand respectively positioned on the plurality of redistributionstructures; and a plurality of storage units electrically coupled to theplurality of center lower bonding pads.

Another aspect of the present disclosure provides a method forfabricating a semiconductor device including providing a first substrateincluding a functional unit; forming a plug structure on the firstsubstrate and electrically coupled to the functional unit; forming afirst redistribution layer above the first substrate; forming a firstlower bonding pad on the first redistribution layer; forming a secondlower bonding pad on the plug structure, wherein the first substrate,the plug structure, the first redistribution layer, the first lowerbonding pad, and the second lower bonding pad together configure a firstchip; and bonding a second chip onto the first chip. The second chipincludes a first upper bonding pad bonded on the first lower bondingpad, a second upper bonding pad bonded on the second lower bonding pad,and a plurality of storage units electrically coupled to the first upperbonding pad and the second upper bonding pad.

Due to the design of the semiconductor device of the present disclosure,data signal may be transmitted through the first upper bonding pad 241,the first lower bonding pad 151, and the first redistribution layer 131without passing through the conductive features, the plug structure 121,and functional units of the first chip 100. As a result, the distance oftransmittance may be reduced so that the performance of thesemiconductor device 1A may be improved. In addition, the powerconsumption of the semiconductor device 1A may be reduced due to theshorter distance of transmittance.

Although the present disclosure and its advantages have been describedin detail, it should be understood that various changes, substitutionsand alterations can be made herein without departing from the spirit andscope of the disclosure as defined by the appended claims. For example,many of the processes discussed above can be implemented in differentmethodologies and replaced by other processes, or a combination thereof.

Moreover, the scope of the present application is not intended to belimited to the particular embodiments of the process, machine,manufacture, composition of matter, means, methods and steps describedin the specification. As one of ordinary skill in the art will readilyappreciate from the disclosure of the present disclosure, processes,machines, manufacture, compositions of matter, means, methods, or steps,presently existing or later to be developed, that perform substantiallythe same function or achieve substantially the same result as thecorresponding embodiments described herein may be utilized according tothe present disclosure. Accordingly, the appended claims are intended toinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, and steps.

What is claimed is:
 1. A semiconductor device, comprising: a first chipcomprising: a first inter-dielectric layer positioned on a firstsubstrate; a plug structure positioned in the first inter-dielectriclayer and electrically coupled to a functional unit of the first chip; afirst redistribution layer positioned on the first inter-dielectriclayer and distant from the plug structure, wherein a top surface of theplug structure is positioned between a top surface of the firstredistribution layer and a bottom surface of the first redistributionlayer; a first lower bonding pad positioned on the first redistributionlayer; a second lower bonding pad positioned on the plug structure,wherein the second lower bonding pad has a protrusion portion downwardlyextended toward the plug structure; a third barrier layer having abottom surface in direct contact with the top surface of the firstredistribution layer, wherein the third barrier layer has a U-shapedcross-sectional profile to receive the second lower bonding padtherewithin and a U-shaped protrusion downwardly extended through thetop surface of the first redistribution layer to receive the protrusionportion of the second lower bonding pad and to direct contact with thetop surface of the plug structure, such that a bottom surface of theU-shaped protrusion is in direct contact with the top surface of theplug structure and is positioned between the top surface of the firstredistribution layer and the bottom surface of the first redistributionlayer; and a second chip positioned on the first chip and comprising: afirst upper bonding pad positioned on the first lower bonding pad; asecond upper bonding pad positioned on the second lower bonding pad; anda plurality of storage units electrically coupled to the first upperbonding pad and the second upper bonding pad.
 2. The semiconductordevice of claim 1, wherein the first chip is configured as a logic chipand the second chip is configured as a memory chip.
 3. The semiconductordevice of claim 2, wherein the plug structure comprises a bottom plugpositioned on the first substrate, a landing pad positioned on thebottom plug, and a top plug positioned between the landing pad and thesecond lower bonding pad, wherein a top surface of the top plug isformed as the top surface of the plug structure to be positioned betweenthe top and bottom surfaces of the first redistribution layer.
 4. Thesemiconductor device of claim 3, further comprising a first barrierlayer positioned between the top plug and the second lower bonding pad.5. The semiconductor device of claim 3, further comprising a secondbarrier layer positioned between the landing pad and the top plug,wherein the second barrier layer has a U-shaped cross-sectional profileto receive the top plug therewithin, wherein a top surface of the secondbarrier layer is positioned between the top and bottom surfaces of thefirst redistribution layer.
 6. The semiconductor device of claim 3,further comprising a fourth barrier layer positioned between the firstlower bonding pad and the first redistribution layer, wherein the thirdbarrier layer is positioned between the top plug and the second lowerbonding pad, wherein the bottom surface of the U-shaped protrusion is indirect contact with the top surface of the top plug, wherein the thirdbarrier layer has a U-shaped cross-sectional profile to receive thesecond lower bonding pad therewithin.
 7. The semiconductor device ofclaim 6, wherein the bottom surface of the U-shaped protrusion of thethird barrier layer is a flat surface and is at a vertical level lowerthan the top surface of the first redistribution layer.
 8. Thesemiconductor device of claim 3, wherein a width of the first chip and awidth of the second chip are substantially the same, wherein a width ofthe landing pad is greater than a width of each of the top plug and thebottom plug.
 9. The semiconductor device of claim 3, wherein the bottomplug comprises aluminum, copper, or a combination thereof, and the topplug comprises tungsten.
 10. The semiconductor device of claim 7,wherein the third barrier layer comprises titanium and titanium nitride,wherein the fourth barrier layer has a U-shaped cross-sectional profileto receive the first lower bonding pad therewithin, wherein a width ofthe first upper bonding pad is greater than a width of the first lowerbonding pad.
 11. The semiconductor device of claim 10, wherein theplurality of storage units are configured as a capacitor array or afloating array.